I use different threads in my Viking, for instance I was making FSL Easter baskets and ornaments and didn't really need the shine that rayon gives so I used the cone thread for sergers. It took me a while to figure out that I needed to use 2 layers of WS stabilbizer and a sharp needle but I got it to work. I've used my Aurifil if I had a small area of a design and didnt have the right color in emb thread, etc. Labels, I do in cotton thread. It's your machine and if you find what you like go for it. Especially if you are practicing a design, who wants to spend good money on thread for a practice piece. My machine likes all thread so I never have a problem, once in a while I might have to sit the spool on the table or in a cup behind the machine for it to work, but it does work. Metallic thread works well if you turn it upside down in a cup on the table, if you are having issues with it. Good luck. When buying emb thread I try to get different shades of the same color because just about every design I've used has some shading in them so I'll get say like 3 different greens, one just a little off in color to the other one. This has worked well for me.